Fix screen being deleted on resize

Also fix crash when resizing the altbuf

kitty/rewrap.h

@@ -27,8 +27,10 @@
 #define next_dest_line(continued) \
     if (dest_y >= dest->ynum - 1) { \
         linebuf_index(dest, 0, dest->ynum - 1); \
-        linebuf_init_line(dest, dest->ynum - 1); \
-        historybuf_add_line(historybuf, dest->line); \
+        if (historybuf != NULL) { \
+            linebuf_init_line(dest, dest->ynum - 1); \
+            historybuf_add_line(historybuf, dest->line); \
+        }\
     } else dest_y++; \
     init_dest_line(dest_y); \
     dest->continued_map[dest_y] = continued;

kitty/screen.c

@@ -104,8 +104,6 @@ static bool screen_resize(Screen *self, unsigned int lines, unsigned int columns
 
     self->lines = lines; self->columns = columns;
     self->margin_top = 0; self->margin_bottom = self->lines - 1;
-    screen_reset_mode(self, DECOM);
-    // TODO: resize history buf
     return true;
 }